R2.3 How far? The extent of chemical change (SL)
15 revision questions with answers for R2.3 How far? The extent of chemical change (SL). Read them here, or play the set as a class game on the projector. Free to host, and students join with a code.
State where forward and reverse rates are equal and concentrations are constant?
- Dynamic equilibriumRight answer
- Static equilibrium
- Completion
- Saturation
What this set covers
Equilibrium at SL: dynamic equilibrium in a closed system, writing Kc, what large and small K mean, Le Chatelier's principle for concentration, pressure and temperature, and the compromise conditions in the Haber process.
- Common mix-up
- Students often say a catalyst shifts the position of equilibrium: it speeds both directions equally, so only temperature changes the value of K.
- Revision tip
- For N₂ + 3H₂ ⇌ 2NH₃, predict the shift for each change in turn, then say which also change K.
All 15 questions and answers
State where forward and reverse rates are equal and concentrations are constant?
Answer: Dynamic equilibrium
Equilibrium can only be established in a…?
Answer: Closed system
At equilibrium, the concentrations of reactants and products are…?
Answer: Constant
Kc expression for N₂ + 3H₂ ⇌ 2NH₃?
Answer: [NH₃]²/[N₂][H₂]³
A value of K much greater than 1 means that at equilibrium…?
Answer: Products predominate
A value of Kc = 1 × 10⁻¹⁰ means that at equilibrium…?
Answer: Reactants predominate
A system at equilibrium shifts to oppose any change imposed on it: this is…?
Answer: Le Chatelier's principle
Shift in position when pressure is increased for N₂ + 3H₂ ⇌ 2NH₃?
Answer: To the right
Effect of adding a catalyst on the position of equilibrium?
Answer: No effect
More H₂ is added to N₂ + 3H₂ ⇌ 2NH₃ at equilibrium. [NH₃] at the new equilibrium?
Answer: Increases
For an exothermic forward reaction, raising the temperature makes K…?
Answer: Decrease
Only factor that changes the value of K for a given reaction?
Answer: Temperature
Pressure has no effect on H₂(g) + I₂(g) ⇌ 2HI(g) because each side has…?
Answer: Equal gas amounts
N₂O₄ (colourless) ⇌ 2NO₂ (brown), ΔH = +57 kJ mol⁻¹. On heating, the mixture turns…?
Answer: Darker brown
The Haber process uses a moderate temperature as a compromise between yield and…?
Answer: Rate
Play it as a class game
Play this set opens it in splycr, where you can host it for your class straight away. Hosting needs no account: put the room code on the projector, and students join from a phone with the code and their first name. Each question plays as multiple choice, and the three wrong options were written for that question.